This invention relates to automatic wiring of electrical circuit boards, and more particularly to apparatus for making solder connections and for detaching errors in the wiring and soldering procedure.
Heretofore, various techniques have been proposed for making circuit connections between board mounted electrical components. The most widely used technique is the printed circuit board in which circuit elements are mounted on insulated boards and connections are made by soldering leads of the element to conductive paths plated onto the boards. The circuit paths on each side of the board can be interconnected by means of plated-through holes. The resulting assembly is typically referred to as a "printed circuit". This technique has disadvantages in that it has a low packing density of circuit elements and requires expensive and time consuming art work for designing the conducting paths.
Another approach is the technique of wire wrapping. Conductive pins with square or rectangular cross-sections extend from circuit components and are interconnected by tightly wrapping an insulated wire about the pin. The wire must be wrapped tightly about the pin to insure contact at the sharp corners. This technique requires an inventory of variously sized sockets and tools to perform the interconnection process. In addition, where insulated wire is used, it is necessary to pre-strip the ends of each wire. These characteristics result in a very high unit cost per electrical connection.
In order to reduce costs and avoid the disadvantages associated with the above techniques, an interconnection process of wire stringing has been developed as described in U.S. Pat. Nos. 3,626,086 and 3,825,999 to Rubey. These patents show the stringing of insulated wire between protruding fingers attached to plated pads on a circuit board. The connecting leads of circuit components are soldered to the pads which are interconnected by the stringing of the wire.
The latter patent discloses a method and apparatus for forming electrical connections to circuit components using wire stringing wherein aligned conductive areas are plated onto opposite sides of an insulated board and are interconnected by means of a plated-through hole. T-shaped guide strips are used to guide and support the interconnecting wire along predetermined paths. The connection terminals are heated to remove the insulation from the wire and to melt solder thereby joining the wire to the terminal. And as a final step, unnecessary interconnections are removed by cutting the insulated wire at selected points.